Showing posts with label UMBILICAL. Show all posts
Showing posts with label UMBILICAL. Show all posts
Wednesday, January 13, 2010
FIBER OPTICS - UMBILICAL
Physical Basis for Optical Fiber Transmission • Fiber Construction: Step Index and Graded Index Types • Numerical Aperture: Light Collection Ability • Modal Structure • Fiber Losses and Signal Attenuation
Fiber Optic Strain Sensors • Intensity Modulated Sensors • Interferometric Fiber Optic Sensors • Fiber Optic Rotation Sensors
Fundamental of fiber optics acoustic sensor • Polarization • Multiplexing • Hydrophone Design • Applications • Non-Acoustic Sensing
telemetry in ocean cable system. The Starting Point—The Deep-Sea Armored Coax • The Nature of Fiber Optic Communications • The Use of Optical Fibers in Ocean Cables • Handling Systems for E-O Cables
International Transport Safety Research
The International Atomic Energy Agency (IAEA), periodically publishes the Regulations for the Safe Transport of Radioactive Materials, which serve as regulations for its own activities and as a model for regulations issued by international organizations and domestic regulatory bodies throughout the world. In order to support technical considerations for revisions to these Regulations, the IAEA may undertake “Coordinated Research Programs in which Member States and international organizations may offer to participate. Five such programs are currently active in the area of radioactive material transport safety, and the purpose and status of each of these is discussed in this paper.
INTRODUCTION
The International Atomic Energy Agency’s (IAEA) “Regulations for the Safe Transport of Radioactive Material” form a consistent, technically robust basis for international and national regulations governing the packaging and transport of radioactive materials. Changes to the IAEA regulations occur periodically, and can be expected to be reflected in international modal requirements and national regulations. Thus, the IAEA’s Transport Regulations have direct impacts on shippers and carriers of these materials.
Since their inception in 1961, the IAEA Transport Regulations have been periodically revised to keep them technically up to date and consistent with modern transportation operations technologies. These revisions are typically based on proposals made by Member States and International Organizations. They may include changes which are based on research results. In cases where proposals for change require additional supportive information, the IAEA can undertake “Coordinated Research Programs” (CRPs) to address the relevant areas. A CRP typically involves 5-7 Member States contributing their research efforts on a defined topic and the preparation of a consolidated report of the results.
There are several CRPs which are either ongoing or have been completed but have not yet been finally published. These CRPs may result in new regulatory requirements being developed and may form the basis for proposals to change the regulations.
Electro-optical Umbilical for 6000m water depths
At 6000m depths, special attention has to be paid to cable weight and outer diameter, as they are the main contributors to the mechanical forces acting on the top section of the cable. At the bottom section, the hydrostatic pressure has to be considered. It is also important to minimise the cable outer diameter in order to reduce the hydrodynamic forces acting on the cable. On the other hand, the ROV power consumption limits the acceptable voltage drop. This leads to an evaluation of cable heating vs. Cu cross-section.
Power conductors
There are several considerations regarding choosing the right power conductor. The overall
target of reducing weight and dimension encourages low cross section power conductors. However, the required voltage at the load and the line current leads to a maximum acceptable voltage drop. Also, cable heating can be significant if several cable layers remain on the winch. The cable temperature depends on the heat transfer through the different materials, and might lead to cable degradation.
The Development of a Cable Termination System for Deepwater Applications
As oil and gas production projects move into deeper waters, new key enabling technologies are required to terminate electrical, optical and hybrid subsea cables. Two failure modes have been identified using current commercially available termination technology in deepwater applications; core element collapse into an atmospheric breakout region and wicking of the compensating fluid from the termination into the interstices of the cable elements. Either failure may lead to partial or catastrophic failure of the termination. Each failure mode can be directly linked to the interaction of the cable elements with the pressure-balanced dielectric fluidfilled splice region in the termination.
Both of these failure modes have been encountered in the recent past during the installation phase of ultra-deepwater developments. In each instance, an understanding of the failure mode led to the development of design modifications that were qualified and successfully deployed. The difficult lessons learned from these experiences have resulted in new design considerations and more rigorous qualification procedures during the development of cable specific Field
Installable Termination Assemblies (FITAs). These lessons have also been cause to rethink the design philosophy of cable terminations. Ocean Design, Inc. (ODI) has embarked on a design program to eliminate the limitations of the current technology and increase the reliability of their terminations.
The result of this effort is the FACT (Field Assembled Cable Termination) system, a modularized termination system that completely isolates the cable’s internal elements from all pressurized
fluid interfaces.
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